Methods and apparatus for folding sheets

ABSTRACT

A method for folding a moving sheet along a fold line which is angled relatively to the direction of movement of the sheet is disclosed. The moving sheet is passed and folded over a round rod having its longitudinal axis parallel to the direction of movement of the sheet. An apparatus for carrying out this method is also disclosed.

United States Patent Van Ma-nen [45'] July 25, 1972 METHODS AND APPARATUS FOR [56] References Cited.

F LDING SHEETS e 0 UNITED STATES PATENTS [72] Inventor: Jacob Teunis Teunissen Van Manen, Johannesburg, South Africa 2,169,345 8/1939 Kuchler ..93/49 M 2,899,873 8/1959 La Bombard ..93/52 [73] Assigneez Conical Containers Company (Proprietary) Limited, Johannesburg, South Africa Primary Examiner Bemard Stickney [22] Filed: May 19, 1971 Attorney-Young& Thompson [21] App]. No.: 144,783 57] ABSTRACT A method for folding a moving sheet alonga fold line which is [30] Foreign Application Priority Data angled relatively to the direction of movement of the sheet is May 1 9, 1970 South Africa ..70/3381 disclosed. The moving sheet is passed and folded over a round rod having its longitudinal axis parallel to the direction of [52] 11.8. C1 .93/49 M, 93/52 movement f the sheet. An apparatus forcarrying out this method is also disclosed. [58] Field of Search ..93/49 R, 49 M, 52

8 Claims, 3 Drawing Figures PATENTEDJum I912 8.678.814

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Fig I Fig.3

1 METHODS AND APPARATUS FOR FOLDING SHEETS The present invention relates to the folding of sheets.

When moving a sheet through a folding machine it is easy enough to ensure that the sheet will fold about a fold line which is parallel with the direction of movement of the sheet. However it is a very different matter when a sheet is to be folded about a fold line which is angled relatively to the direction of travel of the sheet through a folding machine.

There is a very real possibility that the sheet will tend to fold about an imaginary line parallel with the direction of travel of sheet and not about the fold line in question. This means faulty folding which deleteriously affects the folding operation, particularly where high speeds are used.

It is an object of the present invention to provide a new method of folding a moving sheet about a fold line which is angled relatively to the direction of movement of the sheet.

It is another object of the invention to provide apparatus for carrying out the method.

A method of folding a moving sheet about a line which is angled relatively to the direction of movement of the sheet, includes the step of passing and folding the sheet over a curved surface having its axis of curvature parallel to the direction of movement of the sheet.

Apparatus according to the invention includes a curved surface over which the sheet is adapted to be passed and folded, the axis of curvature of the surface being parallel to the direction of movement of the sheet.

While any curved surface may be used, an arcuate surface is preferable.

While the invention may be used in any suitable sheet folding operation, the invention finds particular application in the construction of tapered cartons from blanks.

The present invention is further described with reference to the accompanying drawings which illustrate by way of example a preferred embodiment of the invention as applied to the construction of tapered cartons from blanks and in which:

FIG. 1 shows a blank from which a tapered carton is to be constructed,

FIG. 2 is a diagrammatic plan view of one embodiment of the apparatus of the invention, and

FIG. 3 is a diagrammatic view along the line 33 of FIG. 2.

A blank is divided by means of fold lines 10, 11 and 12 and 12a into four side panels 13, 14, 15 and 16, the side panel 16 including an underlap 16a. Each of the side panels 14, 15 and 16 is tapered but the sides of the side panel 13 are parallel. The upper and lower ends of each side panel provide the top and bottom end closures of the carton respectively but a description of these is unnecessary for a proper understanding of the invention.

The blank of FIG. 1 is formed into a carton in several stages. Firstly the side panel 16 together with the underlap 16a is folded back on the blank along the fold line 12. Heat is then applied to the free edges of the underlap 16a and the panel 13 which are now parallel to each other. Thereafter the side panel 13 is folded back on itself so that the two heated edges are in register with each other. Finally the folded blank is passed between pressure rollers to bond the two heated edges to each other.

All of the steps mentioned above take place in a single machine and the resulting product is an elongated tube which tapers in cross-section.

The lower end of the tube is then formed into a bottom end closure, the carton is filled, and finally, the upper end of the carton is sealed.

The present invention concerns the first folding step i.e. the folding back of the side panel 16 with the underlap 16 about the fold line 12.

In FIG. 2 a newly-formed blank of the type illustrated in FIG. 1 is shown at position 20 and is about to be moved in the direction of the arrow A through a blank folding and sealing machine. From the position 20 the blank is gripped by a set of pinch belts 22 and moved by the pinch belts 22 over a flat elon ated supporting surface 24.

T e blank IS arranged to be orientated so that the free edge of the panel 13 and the fold line 10 are both parallel to the direction of movement of the blank.

Attached along a portion of the left hand side of the supporting surface 24 is a round rod 26 arranged with its longitudinal axis parallel to the direction of travel of the blank.

To the left of the rod 26 is a conventional twist rail 28 for folding back a portion of a carton blank on itself.

In use, the blank is moved from its position at 20 over the supporting surface 24, and the rod 26 with the trailing edge of the fold line 12 in the region of the junction between the supporting surface 24 and the rod 26. As it moves over the surface 24 the twist rail 28 will urge the side panel 16 together with the underlap 16a downwards breaking the line 12. At this point the fold line 12 will lie diagonally across the upper portion of the rod 26. The twist rail 28 will continue to fold the panels 16 and 1611 back on panel 15 and the rod 26 is now shaped as at 27 so as not to obstruct panels 16 and 16a and the flat folding of line 12.

It has been found that the side panel 16 will always fold about the line 12 despite the fact that the line 12 is angled relative to the direction of travel of the blank.

-lclaim:

l. A method of folding a moving sheet along a fold line which is angled relatively to the direction of movement of the sheet, including the step of passing and folding the sheet over a curved surface having its axis of curvature parallel with the direction of movement of the sheet.

2. A method as claimed in claim 1 in which the curved surface is an arcuate surface.

3. A method as claimed in claim 1 in which the sheet is a blank for a tapered carton.

4. Apparatus for folding a moving sheet along a fold line angled relatively to the direction of movement of the sheet, including a curved surface, means for passing the sheet over the curved surface and means for folding the sheet over the curved surface, the curved surface having its axis of curvature parallel to the direction of movement of the sheet over the curved surface.

5. Apparatus as claimed in claim4 in which the curved surface is an arcuate surface.

6. Apparatus as claimed in claim 5 in which the arcuate surface is formed by a portion of the periphery of a round rod.

7. Apparatus as claimed in claim 4 in which the means for passing the sheet over the curved surface includes a set of pinch belts.

8. Apparatus as claimed in claim 4 in which folding means comprises a twist rail parallel to the axis of curvature of the curved surface. 

1. A method of folding a moving sheet along a fold line which is angled relatively to the direction of movement of the sheet, including the step of passing and folding the sheet over a curved surface having its axis of curvature parallel with the direction of movement of the sheet.
 2. A method as claimed in claim 1 in which the curved surface is an arcuate surface.
 3. A method as claimed in claim 1 in which the sheet is a blank for a tapered carton.
 4. Apparatus for folding a moving sheet along a fold line angled relatively to the direction of movement of the sheet, including a curved surface, means for passing the sheet over the curved surface and means for folding the sheet over the curved surface, the curved surface having its axis of curvature parallel to the direction of movement of the sheet over the curved surface.
 5. Apparatus as claimed in claim 4 in which the curved surface is an arcuate surface.
 6. Apparatus as claimed in claim 5 in which the arcuate surface is formed by a portion of the periphery of a round rod.
 7. Apparatus as claimed in claim 4 in which the means for passing the sheet over the curved surface includes a set of pinch belts.
 8. Apparatus as claimed in claim 4 in which folding means comprises a twist rail parallel to the axis of curvature of the curved surface. 